python list comprehensions; compressing a list of lists?

Question

guys. I\'m trying to find the most elegant solution to a problem and wondered if python has anything built-in for what I\'m trying to do.

What I\'m doing is this. I

Answer 1

You can have nested iterations in a single list comprehension:

[filename for path in dirs for filename in os.listdir(path)]

which is equivalent (at least functionally) to:

filenames = []
for path in dirs:
    for filename in os.listdir(path):
        filenames.append(filename)